The opening recitation of Nichirenshū is already translated by Senchū Murano. Here is the translation:

The most profound and wonderful teaching is presented in this sutra. This sutra is difficult to meet even once in thousands and millions of aeons. Now we have been able to see, hear, receive and keep this sutra. May we understand the most excellent teaching of the Tathagata (Buddha).The most excellent teaching of the Great Vehicle is very difficult for us to understand. We shall be able to approach enlightenment when we see, hear, or touch this sutra. Expounded is the Buddha’s truth. Expounding is the Buddha’s essence. The letters composing this sutra are the Buddha’s manifestation. Just as perfume is caught by something put nearby, so shall we richly benefit by this sutra, even when we are not aware of the benefit because infinite merits are accumulated in this sutra.Anyone can expiate his sin, do good deeds, and attain Buddhahood by the merits of this sutra. It does not matter whether he is wise or not, or whether he believes the sutra or rejects it. This sutra is the most wonderful and most excellent taught by the Buddhas of the past, present, and future. May we meet and receive it, birth after birth, world after world.

(taken from here - there is also more on the development of this text)